MUSCLES ENGAGED Back (upper) You can’t see your back without a lot of effort, but this doesn't mean you shouldn’t train it. Back exercises consisting of both back stretching and back strengthening is very important to your health and overcoming back pain. Shoulders The shoulder is the most movable joint in the body. However, it is an unstable joint because of the range of motion allowed. This instability increases the likelihood of joint injury, often leading to a degenerative process in which tissues break down and no longer function well. Equipment Used Stability Ball A stability or exercise ball is a ball constructed of soft elastic and filled with air until firm.Most stability balls range from a diameter of approximately 35 to 85 centimeters (14 to 34 inches). Dumbbells The dumbbell, a type of free weight, is a piece of equipment used in weight training. It can be used individually or in pairs (one for each hand). Dumbbells vary in weight from 3lbs. up to 150lbs. Exercise Instructions Step 1 Kneel on the stability ball and place one hand in front of your knee to maintain good posture, a straight back and stable core. Hold a dumbbell in the opposite arm. Step 2 Lift the dumbbell up the side of the body and contract the muscles in the mid back, shoulder blades and rear shoulder until you have reached a 90 degree angle in the elbow joint. Step 3 Lower the dumbbell back to the starting position and repeat the action.